1. Field of the Invention
The present invention relates to improvements to means for protecting support structures or similar against shocks applied thereto, the devices for fixing these protecting means to the structures which they are intended to protect, and more particularly the devices for fixing what are usually called "alongside fenders" to offshore installation pylons or to the ground such as platforms, docks, risers, drilling barges, pylons, quays, etc.
2. Description of the Prior Art
The "alongside" fenders meant more particularly for offshore works, known in the prior art, are generally formed by rubber pieces having a .DELTA., D or M profile, fixed to a plate which is itself bolted to another plate integral with the structure to be protected, more especially when it is a question of a non flat and in particular cylindrical structure, in a sea environment, the metal systems for securing the rubber protecting pieces to the structure to be protected undergoing intensive corrosion, more especially in the "splash zones" so that the securing bolts do not hold very well and must be frequently replaced, which is time-consuming work.
On the other hand, the fitting of such fenders to a tubular structure presents great difficulties because of the curvature of the strucutre to be protected, so that positioning a plate between the structure and the fender is obligatory. However, the forces to which the fenders are subjected are transmitted unequally to the structures to be protected, because of the methods of fixing the plates to said structures, which involves gussets and zones where the structures to be protected are subjected to particularly high stresses, which are prejudicial thereto.
Proposals have also been made for providing the support structures to be protected with inflatable fenders, formed by a cushion fixed to the structure, for example tubular, to be protected by means of a plate or chains or other cable systems. Since the envelope of these cushions is fragile, it must be protected by a shield, which considerably complicates the design and fitting of this type of fender. Moreover, with inflatable cushions, these fenders must be maintained under constant uniform pressure, whence the need for a permanent pressure check.
Fender systems are moreover known having three components which are fixed to the tubular structure to be protected by means of a collar and which comprise one telescopically sliding component, connected directly to the collar and a second component disposed above the first one and fixed to the structure to be protected by means of a welded or clamped plate, these two components being joined together by a vertical tube on which are fitted rings, excentric for example, which absorb the shocks by deformation.
All these protection systems have the common drawback of requiring, for fixing them to the structures to be protected, means which are complex, difficult to put in place and relatively fragile.